Method and apparatus for configuring content in a broadcast system

ABSTRACT

A method and an apparatus are provided for configuring content in a broadcast system. The method includes receiving a media processing unit (MPU) including a data part and a control part, the MPU being processed independently, wherein the data part includes media data and the control part includes parameters related to the media data; and processing the received MPU, wherein the MPU comprises at least one fragmentation unit, wherein the parameters comprise a first parameter indicating a sequence number of the MPU, and wherein the sequence number of the MPU is unique to where the MPU belongs.

PRIORITY

This application is a Continuation Application of U.S. patentapplication Ser. No. 13/421,375, filed on Mar. 15, 2012, and claimspriority under 35 U.S.C. § 119(a) to Korean Patent Application SerialNo. 10-2011-0023578, which was filed in the Korean Industrial PropertyOffice on Mar. 16, 2011, the entire content of which is incorporatedherein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates generally to a method and an apparatus forconfiguring content in a broadcast system, and more particularly, to amethod and an apparatus for configuring a data unit of content in abroadcast system supporting multimedia services based on an InternetProtocol (IP).

2. Description of the Related Art

A conventional broadcast network generally uses the Moving PictureExperts Group-2 Transport Stream (MPEG-2 TS) for transmission ofmultimedia content. The MPEG-2 TS is a representative transmissiontechnique that allows a plurality of broadcast programs (a plurality ofencoded video bit streams) to transmit multiplexed bit streams in atransmission environment having errors. For example, the MPEG-2 TS isappropriately used in digital TeleVsion (TV) broadcasting, etc.

FIG. 1 illustrates a layer structure supporting a conventional MPEG-2TS.

Referring to FIG. 1, the conventional MPEG-2 TS layer includes a mediacoding layer 110, a sync (synchronization) layer 120, a delivery layer130, a network layer 140, a data link layer 150, and a physical layer160. The media coding layer 110 and the sync layer 120 configure mediadata to a format usable for recording or transmission. The deliverylayer 130, the network layer 140, the data link layer 150, and thephysical layer 160 configure a multimedia frame for recording ortransmitting a data block having the format configured by the sync layer120 in/to a separate recording medium. The configured multimedia frameis transmitted to a subscriber terminal, etc., through a predeterminednetwork.

Accordingly, the sync layer 120 includes a fragment block 122 and anaccess unit 124, and the delivery layer 130 includes an MPEG-2 TS/MPEG-4(MP4) Real-time Transport Protocol (RTP) Payload Format/File deliveryover unidirectional transport (FLUTE) 132 block, an RTP/HyperTextTransfer Protocol (HTTP) block 134, and a User Datagram Protocol(UDP)/Transmission Control Protocol (TCP) block 136.

However, the MPEG-2 TS has several limitations in supporting multimediaservices. Specifically, the MPEG-2 TS has limitations of inefficienttransmission due to unidirectional communication and a fixed size of aframe, generation of an unnecessary overhead due to the usage of atransport protocol, and an IP specialized for audio/video data, etc.

Accordingly, the newly proposed MPEG MEDIA Transport (MMT) standard hasbeen proposed by MPEG in order to overcome the above-describedlimitations of the MPEG-2 TS.

For example, the MMT standard may be applied for the efficienttransmission of complex content through heterogeneous networks. Here,the complex content includes a set of content having multimedia factorsby a video/audio application, etc. The heterogeneous networks includenetworks in which a broadcast network and a communication networkcoexist.

In addition, the MMT standard attempts to define a transmissiontechnique that is friendlier to an IP that is a basic technique in atransmission network for the multimedia services.

Accordingly, the MMT standard attempts to representatively provideefficient MPEG transmission techniques in a multimedia serviceenvironment that changes based on the IP, and in this respect, thestandardization and continuous research of the MMT standard have beenprogressed.

FIG. 2 illustrates a conventional layer structure of an MMT system fortransmission of a multimedia frame according to multi-service/contentthrough heterogeneous networks.

Referring to FIG. 2, an MMT system for configuring and transmitting amultimedia frame includes a media coding layer 210, an encapsulationlayer (Layer E) 220, delivery layers (Layer D) 230 and 290, a networklayer 240, a data link layer 250, a physical layer 260, and controllayers (Layer C) 270 and 280. The layers include three technique areas,Layer E 220, Layers D 230 and 290, and Layers C 270 and 280. Layer E 220controls complex content generation, Layers D 230 and 290 control thetransmission of the generated complex content through the heterogeneousnetwork, and Layers C 270 and 280 control consumption management and thetransmission management of the complex content.

Layer E 220 includes three layers, i.e., MMT E.3 222, MMT E.2 224, andMMT E.1 226. The MMT E.3 222 generates a fragment, which is a basic unitfor the MMT service, based on coded multimedia data provided from themedia coding layer 210. The MMT E.2 224 generates an Access Unit (AU)for the MMT service by using the fragment generated by the MMT E.3 222.The AU is the smallest data unit having a unique presentation time. TheMMT E.1 226 combines or divides the AUs provided by the MMT E.2 224 togenerate a format for generation, storage, and transmission of thecomplex content.

Layer D includes three layers, i.e., MMT D.1 232, MMT D.2 234, and MMTD.3 290. The MMT D.1 232 operates with an Application Protocol (AP)similarly functioning to the RTP or the HTTP, the MMT D.2 234 operateswith a network layer protocol similarly functioning to the UDP or theTCP, and the MMT D.3 290 controls optimization between the layersincluded in Layer E 220 and the layers included in Layer D 230.

Layer C includes two layers, i.e., MMT C.1 270 and MMT C.2 280. The MMTC.1 270 provides information related to the generation and theconsumption of the complex content, and the MMT C.2 280 providesinformation related to the transmission of the complex content.

FIG. 3 illustrates a conventional data transmission layer for abroadcast system.

Referring to FIG. 3, Layer E in a transmission side stores elements ofthe content, such as video and audio, encoded to a Network AbstractionLayer (NAL) unit, a fragment unit, etc., by a codec encoder, such as anAdvanced Video Codec (AVC) and a Scalable Video Codec (SVC) in units ofAUs in layer E3, which is the top-level layer, and transmits the storedelements in the units of AUs to layer E2, which is a lower layer.

In the conventional technique, a definition and a construction of the AUtransmitted from Layer E3 to Layer E2 depend on a codec.

Layer E2 structuralizes a plurality of AUs, encapsulates thestructuralized AUs based on Layer E2 units, stores the encapsulated AUsin the unit of Elementary Streams (ES), and transmits the stored AUs toLayer E1, which is a next lower layer. Layer E1 instructs a relation anda construction of the elements of the content, such as the video andaudio, encapsulates the elements together with the ES, and transmits theencapsulated elements to Layer D1 in units of packages.

Layer D1 divides a received package in accordance with a form suitablefor transmission of the divided package to a lower layer, and the lowerlayer then transmits the packet to a next lower layer.

Layer D in a reception side collects the packets transmitted from thetransmission side to configure the collected packets to the package ofLayer E1. A receiver recognizes elements of the content within thepackage, a relation between the elements of the content, and informationon construction of the elements of the content, to transfer therecognized information to a content element relation/constructionprocessor and a content element processor. The contentrelation/construction processor transfers the respective elements forthe proper reproduction of the entire content to the content elementprocessor, and the content element processor controls elements to bereproduced at a set time and displayed at a set position on a screen.

However, a conventional Layer E2 technique provides only the AU itselfor information on a processing time for the AU reproduction, e.g., aDecoding Time Stamp (DTS) or a Composition Time Stamp (CTS) and a RandomAccess Point (RAP). Accordingly, the utilization of the conventionalLayer E2 technique is limited.

SUMMARY OF THE INVENTION

Accordingly, the present invention is designed to address at least theabove-described problems and/or disadvantages occurring in the priorart, and to provide at least the advantages described below.

An aspect of the present invention is to provide a method of configuringAUs to a data unit for efficient reproduction of the AUs in Layer E2.

In accordance with an aspect of the present invention, a method isprovided for receiving a media processing unit (MPU) including a datapart and a control part, the MPU being processed independently, whereinthe data part includes media data and the control part includesparameters related to the media data; and processing the received MPU,wherein the MPU comprises at least one fragmentation unit, wherein theparameters comprise a first parameter indicating a sequence number ofthe MPU, and wherein the sequence number of the MPU is unique to wherethe MPU belongs.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of the presentinvention will be more apparent from the following detailed descriptiontaken in conjunction with the accompanying drawings, in which:

FIG. 1 is a block diagram illustrating a layer structure for aconventional MPEG-2 TS;

FIG. 2 is a block diagram illustrating an MMT service by a broadcastsystem based on a conventional MMT standard;

FIG. 3 illustrates a conventional data transmission layer diagram in abroadcast system;

FIG. 4 illustrates a conventional reproduction flow of a DU configuredthrough encapsulation of AUs one by one;

FIG. 5 illustrates a conventional process of receiving and reproducing aData Unit (DU);

FIG. 6 illustrates a process of receiving and reproducing a DU accordingto an embodiment of the present invention;

FIG. 7A illustrates a construction of conventional AUs;

FIG. 7B illustrates a construction of AUs according to an embodiment ofthe present invention;

FIGS. 8A and 8B are diagrams illustrating a comparison of a temporalscalability according to a construction of AUs within a DU;

FIGS. 9A and 9B are diagrams illustrating a comparison of anApplication-Forward Error Control (AL-FEC) according to a constructionof AUs within a DU; and

FIG. 10 illustrates a construction of a DU according to an embodiment ofthe present invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Hereinafter, various embodiments of the present invention will bedescribed with reference to the accompanying drawings in detail. In thefollowing description, a detailed explanation of known related functionsand constitutions may be omitted to avoid unnecessarily obscuring thesubject matter of the present invention. Further, the terms used in thedescription are defined considering the functions of the presentinvention and may vary depending on the intention or usual practice of auser or operator. Therefore, the definitions should be made based on theentire content of the description.

In accordance with an embodiment of the present invention, a method isproposed for configuring DUs by grouping a plurality of AUs. The DUs arecontinuously concatenated to become Elementary Streams (ES), whichbecome data transmitted from Layer E2 to Layer E1.

Conventionally, a DU is configured by encapsulating the AUs one by one,a DTS and a CTS are granted to each AU, and a picture type (Intra(I)-picture, Bidirectionally Predictive (B)-picture, or Predictive(P)-picture) of a corresponding AU is expressed in each AU or whether acorresponding AU is a RAP is displayed.

FIGS. 4 and 5 illustrate a reproduction flow of a conventional DUconfigured by encapsulating the Aus, one by one, and FIG. 6 illustratesa reproduction flow of a DU configured with a plurality of AUs accordingto an embodiment of the present invention.

Referring to FIG. 4, when data begins to be received from a center of aDU string (401), because there is a probability that a corresponding DUis not the RAP, i.e., the I-picture, a receiver searches for the RAP,i.e., a DU in a type of I-picture, by continuously examining subsequentconcatenated DUs (402), such that it is possible to initiate thereproduction the DU (403).

In accordance with an embodiment of the present invention, a DU isprovided by grouping a plurality of AUs, and further configuring the DUin units of Group Of Pictures (GOPs), compared to the generation of a DUfor each of the respective AUs. When the DU is configured in the GOPs,all DUs may be independently reproduced, without having to wait until anext DU is decoded, eliminating a complex buffer control requirement.

Further, as illustrated in FIG. 5, when Layer E1 (501) instructsreproduction while limiting a part of an ES, if the DU merely includesone AU, there is no guarantee that the DU corresponding to theinstructed CTS is the I-picture. Therefore, it is necessary for thereceiver to search for DUs prior to the corresponding DU in an inversedirection (502), decode the DUs from the I-picture (503), and reproducethe DU (504), in order to reproduce the DU from an instructed timepoint.

However, in accordance with an embodiment of the present invention, asillustrated in FIG. 6, when the DU is configured in a unit of a GOP (asindicated by a dashed line), the reproduction of the DU from a time(601) instructed in Layer E1 does not require an inverse-directionalsearch of the DUs (602 through 604).

In accordance with an embodiment of the present invention, a DU may beconfigured with a plurality of GOP units. When the DU is configured witha plurality of GOP units, the I-pictures, the P-pictures, and theB-pictures are separately grouped and stored, and the respective datamay be differently stored in three places.

FIG. 7A illustrates a construction of a conventional AU, and FIG. 7Billustrates a construction of an AU according to an embodiment of thepresent invention.

As illustrated in FIG. 7B, when the AUs are grouped according to aproperty and stored in the DU, even if a part of the DU fails to betransmitted during the transmission, it is possible to realize temporalscalability through a frame drop, etc. Further, because a transmissionsystem utilizing an error correction method, such as an AL-FEC, mayutilize a recoverable scope by departmentalizing a scope recoverablewith the AL-FEC into a part including the collected I-pictures, a partincluding the collected PB-pictures, etc., grouping the AUs according toa property and stored them in the DU is also helpful for reducingtransmission overhead due to the AL-FEC.

FIGS. 8A and 8B are diagrams illustrating a comparison of a temporalscalability according to a construction of AUs within a DU between aconventional art and an embodiment of the present invention.

Referring to FIGS. 8A and 8B, when the transmission of the DU isinterrupted or an error is generated during the transmission of the DU,in FIG. 8A, it is impossible to view content after 8 seconds. However,in FIG. 8B, it is possible to view content for up to 14 seconds althoughit has a low temporal scalability.

FIGS. 9A and 9B are diagrams illustrating a comparison of an AL-FECaccording to a construction of AUs within a DU between the conventionalart and an embodiment of the present invention.

As illustrated in FIG. 9A, when the I-pictures, the P-pictures, and theB-pictures are arranged without any consideration to picture type, it isimpossible to identify the construction of the AUs within the DU.Consequently, AL-FEC must then be applied to all durations.

However, in accordance with an embodiment of the present invention, whenthe AUs are arranged according to picture type, because the AUs of theI-picture and P-picture affect a picture quality, it is sufficient toapply AL-FEC only to the AUs in the I-picture and P-picture, asindicated by a thick line of FIG. 9B. Accordingly, the overhead of theAL-FEC is decreased over the remaining durations, i.e., AUs of theB-pictures.

As described above, there are several advantages in the configuration ofthe DU within a unit of a GOP or a plurality of units of GOPs.

FIG. 10 illustrates a construction of a DU according to an embodiment ofthe present invention.

Referring to FIG. 10, the DU includes a header 1001 and a set of AUs1002 included in a GOP or a plurality of GOPs.

The header 1001 includes a DU description 1010, which includesinformation on the DU, an AU structure description 1020, which includesinformation on a construction the AUs 1002, and AU information 1030,which includes information on each AU.

For example, the DU description 1010 may include the followinginformation.

1) Length 1011: This information represents a size of a DU and is avalue obtained by adding a size of headers of remaining DUs and a sizeof a payload after a corresponding field. For example, the Length 1011may be represented in units of bytes.

2) Sequence Number 1012: This information represents a sequence of acorresponding DU within the ES. Omission or duplicate reception betweena plurality of continuous DUs may be identified using the sequencenumber 1012. When an increase of sequence numbers between a previous DUand a continuously received DU exceeds “1”, this indicates that an erroris generated in the transmission of the DU.

3) Type of AU 1013: This information represents a type of AU included inthe DU. For example, the AU may be generally classified into “timeddata” or “non-timed data”, expressed with “0” or “1”, respectively.Timed data, represented by “0”, includes the CTS and/or the DTS andcorresponds to multimedia elements, such as video data and audio data.Non-time data, represented by “1”, includes no CTS or DTS. The non-timedata corresponds to general data, such a picture or a file.

4) Decoding Time of DU 1014: This information represents a time to startdecoding a first AU of the DU, as a representative value.

5) Duration of DU 1015: This information represents a temporal length ofthe DU. A value obtained by adding a duration to the CTS of the first AUof the DU is the same as the time of termination of the reproduction ofthe finally decoded AU of the DU.

6) Error Correction Code of DU 1016: For example, a Cyclic RedundancyCheck (CRC), a parity bit, etc., may be used as a code for errorcorrection.

Further, an AU structure description 1020 may include the followinginformation.

1) Number of AUs 1021: This information represents the number of AUswithin the DU.

2) Pattern of AUs 1022: This information represents a structure and anarrangement pattern of AUs. For example, the Pattern of AUs 1022 may beindicated with values 0: open GOP, 1: closed GOP, 2: IPBIPB, 4:IIPPBB,6: Unknown, or 8: reserved.

Each bit value is added through the OR calculation for use. For example,the construction of IPBIPB of the closed GOP is 1|2=3.

Open GOP, represented by “0”, represents when the GOP is the open GOP.Closed GOP, represented by “1”, represents when the GOP is the closedGOP. Definitions of the open GOP and closed GOP are the same as that ofthe conventional art.

IPBIPB, represented by “2”, represents when I-pictures, P-pictures, andB-pictures are collected based on each group and repeated at least twotimes within the DU, e.g., IPBBIPBB or IPPBBBBIPPBBBB. IIPPBB,represented by “4”, represents when I-pictures, P-pictures, andB-pictures are collected based on each group and repeated only one timewithin the DU, e.g., IIPPBBBB or IIPPPPBBBBBBBB. Unknown, represented by“6”, represents a failure to identify a pattern, and is used in when anorder of AUs is not changed.

Reserved, represented by “8”, represents a value reserved for a lateruser.

3) Size of Patterns 1023: This information represents a size of eachduration of a repeated pattern. For example, when pattern IPBIPB isactually configured as IPPBBBBIPPBBBB, lengths of duration I, durationPP, and duration BBBB are added to be represented as three values inunits of bytes.

The size of the pattern may be expressed as:

-   -   for(i=0;i<number_of_patterns,i++){Size of patterns;}:

Further, the AU information 1030 may include the following information.

1) DTS of AUs 1031: This information represents the DTS of the AU, andmay be expressed as “for(i=0;i<number_of_AUs;i++){Decoding timestamp ofAU;}”.

2) CTS of AUs 1032: This information represents the CTS of the AU, andmay be expressed as “for(i=0;i<number_of_AUs;i++){Composition timestampof AU;}”.

3) Size of AUs 1033: This information represents a size of the AU in theunit of bytes, and may be expressed as“for(i=0;i<number_of_AUs;i++){Size of AU;}”.

4) Duration of AUs 1034: This information represents a temporal lengthof the AU, and may be expressed as“for(i=0;i<number_of_AUs;i++){Duration of AU;}”.

5) AU num of RAP 1035: This information represents a number of the AU,and may be expressed as “for(i=0;i<number_of_RAPs;i++){AU number;}”.

6) Independent and disposable AUs 1036: This information represents arelationship between a corresponding AU and a different AU, and may beexpressed as “for(i=0;i<number_of_AUs;i++){Independent and disposablevalue of AU;}”.

More specifically, when the corresponding AU is dependent on thedifferent AU, a value of the Independent and Disposable AUs 1036 is “1”,when the different AU refers to the corresponding AU, a value of theIndependent and Disposable AUs 1036 is “2”, and when the correspondingAU and the different AU have duplicated information, a value of theIndependent and Disposable AUs 1036 is “4”.

While the present invention has been shown and described with referenceto certain embodiments and drawings thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the spirit and scope of theinvention as defined by the appended claims.

What is claimed is:
 1. A method for receiving media data in a broadcastsystem, the method comprising: receiving a media processing unit (MPU)including a data part and a control part, the MPU being processedindependently, wherein the data part includes media data and the controlpart includes parameters related to the media data; and processing thereceived MPU, wherein the MPU comprises at least one fragmentation unit,wherein the parameters comprise a first parameter indicating a sequencenumber of the MPU, and wherein the sequence number of the MPU is uniqueto where the MPU belongs.
 2. The method of claim 1, wherein theparameters further comprise a second parameter, based on the secondparameter having a first value, the second parameter indicates that theat least one fragmentation unit comprises timed data including timelineinformation for decoding or presentation of content of the timed data,and based on the second parameter having a second value, the secondparameter indicates that the at least one fragmentation unit comprisesnon-timed data, which does not include the timeline information fordecoding or the presentation of the content of the non-timed data. 3.The method of claim 1, wherein at least one packet received through theMPU includes information indicating if the at least one packet includesat least one random access point (RAP).
 4. The method of claim 1,wherein, according to the at least one fragmentation unit comprising thetimed data, a first positioned fragmentation unit in the MPU is a startposition enabling a playback of the media data to be started.
 5. Themethod of claim 1, wherein the media data in the data part correspondsto at least one group of pictures.
 6. The method of claim 1, wherein thecontrol part includes information on a decoding order of each of the atleast one fragmentation unit.
 7. The method of claim 1, wherein if theat least one fragmentation unit comprises timed data, the control partcomprises information on a presentation duration of each of the at leastone fragmentation unit and a presentation order of each of at least onefragmentation unit.